If EMU-integrity is seen as a ‘Maginot line’ for the European project, then we have to be honest about the consequences. Will the citizens of a democracy put up with interminable austerity and rising unemployment? If not, and if EMU-integrity is sacrosanct, then the trilemma suggests that capital controls are the only option, because they can be combined with a fixed currency and internal demand-management policy (reflation). (‘Fixed-currency’ is relevant here despite having a unified currency, because a reflationary policy will require the emission of a parallel legal tender.)
Capital controls would by necessity have draconian ends, for the reasons already stated. But if EMU is seen as inviolable, it might be the unforeseen consequence. Sadly, Europe has been here before — in some respects, precisely here. But that’s another story.